Method of manufacturing a polisher

ABSTRACT

In a method of making a polishing element a photoresist film 2 is first deposited on a surface of metal stock 1. A photomask 3 is then used to selectively cover portions of the deposited photoresist film 2. Thereafter, portions of the photoresist film 2 which are not covered by the photomask 3 are removed in order to leave exposed patterned portions 5 of the metal stock surface. Gulf-shaped recesses 6 are then etched into the exposed portions of the metal stock surface. The formation of gulf-shaped recesses 6 results from the application of a etchant while the metal stock 1 and the etchant are in physical motion relative to one another. After etching, remaining portions of the photoresist film 2 are removed from the metal stock. A polishing element 10 comprising cutting teeth 11 having acute cutting action angles results.

BACKGROUND

This invention relates to a method of manufacturing a polishing element,and particularly to a method of manufacturing an essentiallyall-metallic polishing element useful for finishing surfaces of bothmetal and nonmetal objects.

Polishing tools such as files or sandpapers have traditionally been usedto polish the surfaces of nonmetal objects (like wood, bamboo, orsynthetic resin, for example,) or to polish the surfaces of metalobjects (such as aluminum, brass, copper, steel, or the like).

Files are polishing tools made from metallic stocks which, whenfinished, have teeth formed on one or more surfaces thereof. The teethhave customarily been formed on the files by punching the surfaces ofthe metallic stock with a chisel. Unfortunately, this method is noteasily adaptable to efficient mass-productive techniques. Furthermore,neither the tops of the teeth nor the finished sides of the teeth on thefiles formed by this method are flat and smooth. In this regard, fileshaving teeth whose tops and sides are not flat and smooth aresusceptible to a clogging phenomena which occurs in the recessed partsof the file. Clogging becomes even more apparent when a file is used onnonmetal objects. In addition, due to the extreme difficulty innarrowing the gaps between teeth, files have not generally beenconsidered suitable tools for the final steps required for finefinishing or polishing.

Sandpapers are made by sticking abrasive particles onto a paper or acloth. Sandpapers can be used for final finishing touches since theirfaces have very fine meshes. However, during the polishing operationabrasive particles adhered to sandpapers tend to break loose. Not onlydoes the detachment of the abrasive particles shorten the life of thesandpaper, but the particles which come off are a potential cause offurther problems. While the pliability of sandpaper permits it to beused with a holder, particle detachment occurs even when a holder isemployed.

Whenever a file or sandpaper is utilized, fine scratches can be left ona surface being polished. The arrangement of teeth (in the case of afile) or the arrangement of abrasive particles (which essentiallyfunction as teeth in the case of sandpaper) cannot be strictly regulatedand hence contribute to the fine scratches left on the finished polishedsurface.

A file foil is publicly disclosed in Japanese Pat. No. 51-9958 forovercoming problems such as those described above which attend existingpolishing tools. The file foil is made of metal but is unlike ordinaryfiles which have metal recesses at points where the file teethintersect. That is, on the file foils of Japanese Pat. No. 51-9958 theteeth run without a break on the file surface. In addition, thearrangement of the teeth on the file foils is strictly regulated. Yetthe file foils are thin and generally lack rigidity. Consequently, thefile foils are prone to be damaged.

Some emobdiments of the file foils disclosed in Japanese Pat. No.51-9958 are adapted to mate with a holder for use. However, when theteeth on the file foils are worn-out, the entire unit including both thefile foil and the holder are thrown away. Disposal of the entire unit isneither economical nor advantageous in a waste conscious society. Filefoils adhered to a holder for use as a polishing tool are not always asdurable as desired or are unsuitable for long periods of use. In thisrespect, the non-rigid file foils tend to detach from a holder undercertain conditions of adhesion or very stressful polishing work.

The embodiments of the file foils disclosed in Japanese Pat. No. 51-9958have a cutting action angle (an angle between a top face of a tooth anda side of the tooth) which becomes wider than 90° (i.e., becomes anobtuse angle). A cutting action angle wider than 90° results in a lessthan optimum polishing performance. In fact, in cross section the teethof the file foils disclosed in Japanese Pat. No. 51-9958 are essentiallysemi-circular. The semi-circular shape of the file teeth result from theelectrolytic and reducing methods used in making both the file foil anda metallic mold therefore. In this respect, Japanese Pat. No. 51-9958 isincorporated herein by reference, particularly the steps included in themethod of manufacturing such file foils. With respect to the steps ofthis method, the file foil teeth must be formed in essentiallysemi-circular shape in order to remove the file foil from its associatedmetallic mold. Otherwise, considerable difficulty would arise whenremoving the file foil from the mold. Thus, file foils produced inaccordance with the method of Japanese Pat. No. 51-9958 have cuttingaction angles greater than 90° and teeth which tend to lack the desiredrigidity.

In view of the foregoing deficiencies of existing polishing elements, itis an object of this invention to provide a method of manufacturing anessentially all-metallic polishing element having superb rigidity anddurability.

An advantage of the present invention is the provision of a method ofmanufacturing a polishing element which is easily and economicallymass-produced.

A further advantage of the present invention is the provision of amethod of manufacturing a polishing element whose utilization results insmooth, long-lasting finished surfaces yet which requires lessexpenditure of effort.

SUMMARY

In a method of making a polishing element a photoresist film is firstdeposited on a surface of metal stock. A photomask is then used toselectively cover portions of the deposited photoresist film.Thereafter, portions of the photoresist film which are not covered bythe photomask are removed in order to leave exposed patterned portionsof the metal stock surface. Gulf-shaped recesses are then etched intothe exposed portions of the metal stock surface. The formation ofgulf-shaped recesses results from the application of a etchant while themetal stock and the etchant are in physical motion relative to oneanother. After etching, remaining portions of the photoresist film areremoved from the metal stock. A polishing element comprising cuttingteeth having acute cutting action angles results.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments as illustrated in the accompanyingdrawings in which reference characters refer to the same partsthroughout the various views. The drawings are not necessarily to scale,emphasis instead being placed upon illustrating the principles of theinvention.

FIGS. 1-7 are schematic cross-sectional views depicting process stepssuitable for the manufacture of a polisher according to a mode of theinvention;

FIG. 8 is a perspective view of a polisher having a plurality ofessentially cylindrically-shaped teeth;

FIG. 9 is a perspective view of a polisher with strip-shaped teeth;

FIG. 10 is a perspective view of a polisher with strip-shaped teethintersecting laterally and vertically;

FIG. 11 is a partial, vertical elevation of a polisher with a pluralityof essentially cylindrically-shaped teeth, the polisher being attachedto a holder;

FIG. 12 is a bottom view of FIG. 11;

FIG. 13 is an elevational view of a polisher attached to another typeholder to be used as a polishing tool;

FIG. 14 is a bottom view of FIG. 13;

FIG. 15 is a schematic sectional view of a piece of metal stock having acoarse face; and,

FIG. 16 is a schematic sectional view of a polisher formed by utilizingthe piece of metal stock of FIG. 15.

DETAILED DESCRIPTION OF THE DRAWINGS

According to the modes of the present invention a polishing element ismanufactured by initially selecting a piece of metal stock 1 as astarting material from among various suitable metals of the type whichcan be etched with a etchant. The shape of the metal stock 1 can be, forexample, either that of a plate or a block. In the case of ablock-shaped stock the stock may be either square or round. In anexample shown in FIG. 1, a steel plate is selected as a metal stock 1.

A photoresist film 2 which is resistant to corrosion is coated on thesurface of the metal stock 1 as shown in FIG. 2. It should be understoodthat the resultant abrasive working portion of the polisher need notnecessarily be limited to one side of the metal stock 1 but can, ifdesired, be formed on more than one side of the stock 1. To simply thediscussion with reference to the examples of the illustrations, theabrasive working surface is formed on the front side (upper side) of thesteel plate. However, the reverse side (bottom side) can also befabricated to have an abrasive face.

Next, a "pre-baking" treatment is given to the photoresist film 2.Thereafter a pattern of teeth to be formed in a stock 1 is made with adevice such as a micro-plotter or the like, which is contracted toproduce a precision photo-plate or photomask 3. The photomask 3 has apattern of solid portions corresponding to teeth to be formed in thestock 1 as well as vacant portions between the teeth. The photomask 3 isthen laid over the photoresist film 2 to shield portions of thephotoresist film during an exposure and development step whereinunmasked portions of the photoresist film 2 are removed.

The photoresist film which remained on the metal stock 1 through thedevelopment process is then treated for post-baking. In the post-bakingstep a plurality of openings 4 which positionally correspond with thepattern of vacant portions of the photomask 3 are made on thephotoresist film 2 as illustrated in FIG. 4 to form exposed metallicparts 5 ready for etching.

During etching, exposed parts 5 of the metal stock 1 are chemicallycorroded by application of an etchant. In the etching process relativephysical motion occurs between the stock 1 and the etchant. The relativephysical motion of the stock 1 and the etchant causes the etchant tocorrode more deeply into the metal stock 1 and facilitates lateraletching. That is, the relative physical motion facilitates theundercutting of portions of the metal stock which lie under thephotoresist film 2. The etching results in the formation of a pluralityof gulf-shaped recesses 6 in the metal stock 1 as illustrated in FIGS. 5and 7, for example. A gulf-shaped recess is an arc-like recess (and insome embodiments an essentially semioval shaped recess) formed betweenthe teeth 11. As illustrated in the Figures, each tooth 11 is borderedby the upper surface of metal stock 1 and the arc-like contours of theadjacent recesses 6. A tangent to the etched recess arc near the pointof recess intersection with the upper etched surface of the metal stock1 intersects the surface of the metal stock 1 at an interior angle alpha(α) which is less than 90°.

The relative physical motion of the metal stock 1 and the etchant can beeffected in a number of ways. For example, in one embodiment the metalstock 1 with its exposed part 5 is deposited into a tub filled withetchant and soaked while the metal stock is moved both laterally andvertically. In another embodiment, etchant is sprayed onto a metal stock1 with its exposed parts 5. In FIG. 6, for example, stock 1 with itsexposed parts 5 rotates about its axis A while etchant is sprayed from afixed nozzle B onto the exposed parts 5. The etchant is evenly sprayedonto the exposed parts 5 while the metal stock 1 is rotating, resultingin the formation of gulf-shaped recesses 6 by the etching process.

Alternatively, the metal stock 1 is, in another embodiment, fixed whilenozzle B moves. As another alternative, both the nozzle B and the metalstock 1 rotate. In an even further alternative, a plurality of rotatingnozzzles B are provided and the metal stock 1 remains fixed so thatentire surface of the metal stock 1 including the exposed part 5 issprayed.

After completion of the etching process, the remaining photoresist film2 is removed by conventional techniques.

The above steps of the disclosed method result in the formation of araised tooth 11 between the adjacent gulf-shaped recesses 6 asillustrated in FIG. 7. Thus, a metallic polisher 10 having a pluralityof teeth 11 is obtained.

The teeth 11 on the polisher 10 have flat tops, but the teeth side facesare curved like an arc as described above. The blade 12 is formed at theboundary line or the intersection between the top face and its sideface. The cutting angle α between the top face and the side face is anacute angle. That is, the angle alpha is narrower than 90°. Preferablycutting action angle alpha is in the range of 40°-70°.

The teeth formed on the polisher can be arranged in numerous shapes andpatterns as desired. FIGS. 7 and 8 illustrate an essentiallyall-metallic polisher 10 having essentially circular-shaped teeth 11.The teeth 11 were formed by using a photomask having a plurality ofcircles arranged at set intervals to cover a metal stock 1 of steelhaving a thickness T (T equaling 0.5 mm). In this example, the maximumtooth diameter D is 0.13 mm; tooth height H is 0.13 mm; and, the cuttingaction at angle alpha is 70°.

FIG. 9 illustrates an essentially all-metallic pollisher 20 made from ametal plate with teeth 21 in the shape of raised stripes.

An essentially all-metal polisher 30 illustrated in FIG. 10 is also madefrom a steel plate. The polisher of FIG. 10 has teeth 31 which areformed with raised stripes running both laterally and vertically tointersect one another. Like an embodiment of a file foil disclosed inJapanese Pat. No. 51-9958, the top face of the raised teeth stripesintersect each other. Unlike ordinary files, however, no recesses occurat points where the stripes intersect.

It should be understood that many patterns of teeth can be formed in themetal stock 1 and the number and types of such patterns should not belimited to those mentioned herein. Furthermore, the metal stock need notnecesssarily be of a plate shape. Square, round, or block shaped stockscan be employed. In some embodiments the teeth are even formed on asurface of a block-shaped metal stock which is grasped by or mated witha holder.

Depending upon its thickness, a plate-shaped polisher may havesufficient rigidity to be used in polishing operation without the needof a supporter or holder. A polisher can, of course, be attached to aholder even if it were to have sufficient rigidity in its own right. Theshapes of the holders can very depending on the type of the work or theplace of the work.

When it is to be used in conjuction with a holder, the polisher is cutto an appropriate size and pressed-formed so that it can be easilyattached to the holder. Attachment may be accomplished by variousmethods. For example, FIGS. 11 and 12 show a polishing tool 40 in whicha plate-shaped polisher 10 is attached to a holder 41 using nuts 42.Tool 40 is ideal for polishing a wide plane.

FIGS. 13 and 14 show a polishing tool 50 useful for narrow corners.Accordingly, the polisher 10 is triangle-shaped and the tip of thepolisher is bent so that it can be attached to a hook 52 of the holder51. The rear part of the polisher is secured with a nut 53.

As suggested above, the shapes of the polishing tool can be altereddepending upon the purpose of the tool. For instance, a cylindricalholder can be wrapped with a polisher to polish the inside of a hole.

In various embodiments plate-shaped polishers are secured to holderswhich have surfaces which are either raised or recessed. The polisherscan also be press-formed to form raises or recesses facilitating easierpolishing work on curved surfaces.

Furthermore, for coarse polishing a polisher can be secured to a holderhaving either raised or recessed surfaces or both; or, the plate-shapedpolisher can be pressed-formed to make a raised or recessed surface.

An essentially smooth metal stock is useful for the production ofvarious embodiments of metal polishers, but smooth metal stocks need notbe used exclusively. For instance, as illustrated in FIG. 15, a polishercan be made from a piece of metal stock 1' having a coarse surface. Forthis case, the top face of the tooth 11' remains coarse as shown in FIG.16. The essentially all-metallic polisher 10' facilitates more delicatepolishing work by virtue of its coarse surface.

Other steps are includable along with the methods described above. Forexample, the rigidity of the teeth of a polisher is enhanced when a heattreatment is provided for the surface on which the teeth are formed.Enhanced tooth rigidity assures longer life and better quality of thepolisher. Furthermore, as a quench hardening operation a heat treatmentcan be given only to the surface part of the metal stock upon which theteeth are formed. Inasmuch as quenching is done only to the surface partof the polisher, no difficulty arises when the polisher is bent toconform to a holder as shown in FIGS. 11-14. Thus, the polisher canassume various shapes and undergo deformation after quenching. Ofcourse, if desired, rather than quench the surface part only the wholepart of the polisher may be quenched after the process of shaping iscompleted.

As described above, the present invention provides a method of producinga highly effective polisher. The modes of the method of the presentinvention have various advantages:

The method advantageously employs metal stock and a particularphoto-etching process step to form a polisher. Depending upon theselection of the appropriate metal stock, a rigid essentiallyall-metallic polisher can be made which need not be used with a support.If desired, however, the polisher can be attached to an appropriateholder.

A photo-etching process step of the invention includes the impartationof physical, relative motion to the metal stock and its exposed partswith respect to an etchant to form teeth with an acute cutting angle.Moreover, the process results in a smooth, uniformly finished workingsurface upon the expiration of less effort.

The process of the invention reduces the time reuqired for corrosion dueto the relative motion of the metal stock and its exposed part withrespect to the etchant, thereby shortening the manufacturing time.

If metal stock having a coarse face is employed in the process, the topface of teeth formed on the metal stock remains coarse. Polishingperformance is improved for many jobs by the provision of a coarse face.

A polisher with teeth of enhanced hardness is formed in the mode of theinvention wherein a heat treatment is applied only to the workingsurface on which the teeth are formed. Hardened teeth assure the longerlike and superior quality of the polisher. The polisher may be bent orconformed to a desired shape after the heat treatment.

In another mode of the invention, polishing performance is furtherenhanced by making the top face of the teeth coarse and quenching onlythe coarse abrasive surface.

While the invention has been particularly shown and described withreference to the preferred embodiments thereof, it will be understood bythose skilled in the art that various alternations in form and detailmay be made therein without departing from the spirit and scope of theinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A method of making apolishing element comprising the steps of:depositing a photoresist filmon a coarse surface of metal stock; using a photomask to selectivelycover portions of said photoresist film; removing portions of saidphotoresist film thereby leaving portions of said metal stock coarsesurface uncovered, etching recesses in said uncovered portions of saidmetal stock coarse surface by applying an etchant while said metal stockand said etchant are in physical motion relative to each other, therebyforming cutting teeth having teeth tops lying essentially in the planeof said metal stock coarse surface and teeth sides which at leastpartially define said recess, the interior angle between said teeth topand teeth side being an acute angle; removing remaining portions of saidphotoresist film from said metal stock; and, hardening said coarsesurface of said metal stock on which said cutting teeth are formed. 2.The method of claim 1 wherein said interior angle between said teeth topand teeth side is in the range of 40° to 70°.
 3. The method of claim 2further comprising the step of securing the polishing element to aholder.
 4. The method of claim 1 further comprising the step of:bendingsaid metal stock in conformity to a desired shape.
 5. The method ofclaim 1 further comprising the step of securing the polishing element toa holder.